Changed the config parameter.  The session's _get_time() function has also changed.
diff --git a/system/helpers/date_helper.php b/system/helpers/date_helper.php
index b818da9..131508f 100644
--- a/system/helpers/date_helper.php
+++ b/system/helpers/date_helper.php
@@ -52,7 +52,7 @@
 	{
 		if (empty($timezone))
 		{
-			$timezone = config_item('timezone');
+			$timezone = config_item('time_reference');
 		}
 
 		if ($timezone === 'local' OR $timezone === date_default_timezone_get())